The Administrative Core is essential for the conduct of this Program Project. It will continue to be based in the administrative area of the Hematology-Oncology Division at the University of Pennsylvania. The Core provides administrative support for the participants in the Program Project, as well as secretarial, and consultative functions and the supplies needed to support these functions. In addition, A. Administrative Functions To provide financial coordination for the Program Project, the Core Unit B leader and an experienced business administrator, Ms. Michele Arlotta, monitor the expenditures of each Project and Core Unit, facilitated by a system of computerized record keeping. Project leaders and Core Unit Leaders will be provided with monthly statements of the financial status of their projects or core units. Core Unit B will also serve to centralize the ordering of supplies and equipment, enabling the business administrator to monitor these expenditures and to take advantage of discounted prices available through the University. The business administrator will also oversee matters relating to the consortia with the Division of Hematology at the Children's Hospital of Pennsylvania and Thomas Jefferson University. B. Secretarial functions The Program Project will make use of 35% of the effort of a secretary, Mrs Terese Manganaro, who is based on the 9th floor of BRB 11/111 of the University of Pennsylvania. Mrs. Manganaro will type manuscripts and correspondence generated by the activities of the Program. She has an Apple Macintosh computer and is electronically networked to each investigator via the University of Pennsylvania E-mail network. C. Common Services and Supplies Core Unit B will provide the photocopying, postage, and telephone service needed to support the activities of the Program Project. D. Consultative functions Core Unit B will provide two types of consultative function. First, at monthly intervals, an outside investigator whose interests coincide with those of the members of the Program Project will be asked to a spend a day at the University, meet with the various Project leaders and Co-Investigators, and present a seminar at the weekly Thrombosis & Cardiovascular Biology Seminar. Funds required for these visitors in excess of those requested in the Core Unit Budget will be provided by other funds available to the Hematology-Oncology Division. Second, an External Advisory Committee composed of three members will be selected if and when the Program Project is re-funded. The Committee will be asked to visit the Program Project on a yearly basis, review its progress, and make specific recommendations regarding future directions. E. Continued Supply of Monoclonal Antibodies Since the inception of this Program Project, a Hybridoma Core (Core A), has produced a number of monoclonal antibodies (mAbs) to platelet and endothelial glycoproteins that have been highly useful to the Program. These include: A. Monoclonal antibodies to platelets glycoproteins allbfJS. Multiple antibodies have been produced by the Core to platelet allbbS and continue to be extensively utilized. These include mAbs specific for allb; (33; the allb(33 complex; activation-specific epitopes on the allb(33 complex; antiidiotypic mAbs to the activation-specific, anti allbps mAb PAC-1; and the cytoplasmic domains of allb and (33. B. Monoclonal antibodies to the human thrombin receptor (PAR1). The Core has had a particularly productive track-record in producing mAbs to epitopes on amino terminus of human PAR1 that have been useful in studies of platelets and endothelial cells. C. Monoclonal antibodies to the human PAR2. Antibodies to the PAR2 amino terminus (SAM11 and SAM12) have also been generated from mice immunized with the peptide, SLIGKVDGTSHVTG, corresponding to the first 14 residues of human PAR-2 starting at the activation site (Arg36-Ser37). The mAbs have been particularly useful for flow cytometry and immunohistochemical studies. D. Miscellaneous antibodies. Additional antibodies produced by the Core that have been used by Core members include mAbs to CD9 and the chemokine receptor CXCR4.